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For men who have had or might undergo a vasectomy, there is good news: A major study finds scant evidence that the procedure raises their risk of prostate cancer.

"At most, there is a trivial association between vasectomy and prostate cancer that is unlikely to be causal," concluded a team led by Dr. R. Jeffrey Karnes, of the Mayo Clinic in Rochester, Minn.

The analysis, based on data from 53 studies on the subject, was published online July 17 in the journal JAMA Internal Medicine.

As the researchers noted, couples who want to avoid unintended pregnancy often place the responsibility on the female partner. And sometimes, conception occurs despite the use of birth control pills or devices.

In contrast, vasectomy has a very low risk of unintended pregnancy. And, "given the lower costs and lower risk of complications for vasectomy compared with [female] tubal ligation, it is clear that vasectomy is underused and should be offered more routinely to couples," the researchers suggested.

Vasectomy is typically a 30-minute outpatient procedure where a local anesthetic is applied to the scrotum and a doctor makes a small incision, pulling out the vas deferens (tubes that transport sperm). These tubes are then either cut or blocked before re-insertion, preventing fertilization.

But one potential reason holding some men back from "the snip" could be fears that it might somehow raise their odds for prostate cancer. According to Karnes and colleagues, those fears were stoked in the 1980s and 1990s by isolated reports of an "association between vasectomy and the risk of prostate cancer."

That initial controversy has died down, however, with better-conducted studies in recent years finding no such link. To try to settle the controversy, the Mayo team pored over data from 53 studies conducted across the world, involving a total of more than 14 million men.

The studies typically compared prostate cancer rates for men of similar ages who'd either had a vasectomy or not. Study follow-up varied from just under 2 years to more than 24 years.

The result? Overall, there was no link at all between vasectomy and the "high-grade" aggressive prostate tumors that are a bigger threat to health. There was a "weak association" -- about a 5 percent hike in relative risk -- between vasectomy and any form of prostate cancer, but even that statistic might be due to other factors, the study authors said.

As the integrity and methodology of studies got better, any link between vasectomy and prostate cancer shrank to near zero, the investigators noted.

And even if such a link did exist, the researchers calculated it would translate to only a 0.6 percent rise over a lifetime in the absolute risk of prostate cancer for any one man who underwent a vasectomy.

"It is questionable whether such a small increased risk is important to the public," the study authors said.

Dr. David Samadi is chair of urology at Lenox Hill Hospital in New York City. He read the study and offered up an explanation for even the 0.6 percent rise in risk.

The finding "demonstrates the effects of 'health-seeking' activities among men undergoing vasectomy," he said. "Simply put, men who decide to go with vasectomy [tend to] visit physicians more often and get tested for [prostate-specific antigen] and prostate cancer more often than other men. This conscious health-seeking behavior leads to more prostate cancer diagnoses."

The bottom line, according to the Mayo team, is that "although patients should be appropriately counseled, concerns about the risk of prostate cancer should not preclude clinicians from offering vasectomy to couples seeking long-term contraception."

Samadi agreed. The new study "demonstrates that vasectomy is a safe procedure, which does not increase the chance of prostate cancer in men," he said.